1. Field of the Invention
The present invention relates to a soft magnetic alloy thin film which is suitable for a magnetic head for high density magnetic recording, and more particularly, it relates to a soft magnetic alloy thin film suitable for a magnetic head such as a thin film magnetic head which is manufactured by a low-temperature process.
2. Description of the Background Art
In general, magnetic heads comprising ferromagnetic metal films which are arranged at least in the vicinity of gaps of magnetic cores for improving the recording density have been proposed for use in a computer memory device and a high density magnetic recording/reproducing apparatus such as a video tape recorder (VTR).
While permalloy (Fe-Ni alloy), Sendust (Fe-Al-Si alloy), a Co amorphous alloy and Sofmax (Fe-Ga-Si alloy) have generally been put into practice as materials for ferromagnetic metal films, the coercive force of a recording medium is now being increased for further improvement of the recording density, and improvement of recordability and overwritability is awaited for a recording head. In order to improve recordability and overwritability, it is necessary to increase the saturation magnetic flux density of the ferromagnetic metal film. Under such circumstances, a soft magnetic alloy thin film having a high saturation magnetic flux density is presently being studied.
For example, it has been reported that an Fe-N film with a high saturation magnetic flux density exhibits excellent soft magnetic properties as compared with an Fe film ("Structure and Magnetic Properties of Nitrogen-Added Soft Magnetic Fe Sputtering Film", Digests of the 11th Annual Conference on Magnetics in Japan, p. 230, 3PB-8, Sony Information Systems Research Center). However, this film is disadvantageous in practice due to its inferior heat resistance against a temperature for glass bonding which is employed in a step of manufacturing a magnetic head. As a means for solving this problem, a material is known, which has a high heat resistance and a high saturation magnetic flux density, such as that disclosed in Japanese Patent Laying-Open No. 63-299219 (1988) or 64-42108 (1989), for example, which is improved in heat resistance through addition of a small amount of an element such as Nb, Ta, Zr, Al or Ga to an Fe-N film. This is a soft magnetic alloy film having an extremely high saturation magnetic flux density of at least 18 kG.
A magnetic film which is applied to a head such as a thin film head requiring no bonding step employing glass having a high melting point must exhibit excellent soft magnetic properties without heat treatment. However, a well-known soft magnetic film consisting of Fe-N or the like exhibits a coercive force of about 1 Oe at best, in the as-prepared state, although it has a high saturation magnetic flux density of about 20 kG. Thus, a soft magnetic alloy film exhibiting a coercive force of not more than 0.5 Oe, which is a value applicable to a magnetic head, in the as-prepared state without heat treatment is not yet known in the art.